This invention pertains to a system which can be used to convert images on motion picture film into video signals for use in television transmissions. More specifically, this invention pertains to devices of this type which can be utilized to produce video signals from continuously driven motion picture film, or can be used to produce video signals from motion picture film which is driven discretely, i.e. frame by frame.
Devices which can produce television signals from film projected in a projector are known. However, transmissions produced by some existing devices have a tendency to flicker on a television screen. The reason why such flickering occurs is that the projection speed of a motion picture projector is substantially slower than the vertical deflection or sync pulses. In the event that the projection of the motion picture film is not precisely coordinated with the vertical sync, flickering will occur.
Additionally, some devices of this type are not well suited for projecting motion picture film in both a continuously driven mode and a discretely driven mode. Although in the normal course of events a motion picture film is projected continuously at normal operating speed, it is sometimes desirable to project individual film frames in a stepwise fashion.
Thus, it would be desirable to provide a system of this type which would eliminate flicker from a television transmission when viewed on a television screen, and it would also be desirable to provide a device which would allow single frames to be projected individually in addition to permitting normal continuous drive for a motion picture film.